A mobile terminal is equipped with a backlight for illuminating keys or the like at a key pad part or the like which becomes user interface so that a user can distinguish a key position even in a dark place. It is not necessary to let this backlight light up in an originally bright use environment, but also it consumes wasteful electric power when let it light up.
For this reason, it is considered to prevent consumption of the wasteful electric power by using a mobile terminal equipped with an illuminance sensor (an optical sensor). That is, the illuminance sensor detects illuminance level in a use environment of the mobile terminal by the user. And, the mobile terminal suppresses the power consumption according to the detected illuminance level by turning off the light or making the luminance low when the backlight is unnecessary.
FIG. 12 is a drawing showing an external appearance of a flip-type mobile terminal as related art of the present invention. As shown in FIG. 12, in the flip-type mobile terminal, it is general to arrange the illuminance sensor for controlling a backlight at an inner face of the flip-type housing. Such a flip-type mobile terminal is disclosed by Japanese Patent Application Laid-Open No. 2008-263271, for example. Also, the relating mobile terminals are disclosed in Japanese Patent Application Laid-Open No. 2005-012609, Japanese Patent Application Laid-Open No. 2008-219659, Japanese Patent Application Laid-Open No. 2008-166972 and Japanese Patent Application No. 2007-186220.